A method of producing cement clinker and a second calcined material, wherein the cement clinker is produced in a first production line and the second calcined material is produced from a raw material in a second production line by carrying out the following procedures e) optionally drying the raw material in a dryer, g) calcining the optionally dried raw material in a rotary kiln to obtain the second calcined material, wherein the sensible heat of a hot gas in the first production line is used as a heat source in the calcining step g) for calcining the raw material, and wherein the rotary kiln exhaust gas coming from the calcining step g) is introduced into the first production line for the secondary combustion of the rotary kiln exhaust gas.

A method of producing cement clinker and a second calcined material, wherein the cement clinker is produced in a first production line and the second calcined material is produced from a raw material in a second production line by carrying out the following procedures e) optionally drying the raw material in a dryer, g) calcining the optionally dried raw material in a rotary kiln to obtain the second calcined material, wherein the sensible heat of a hot gas in the first production line is used as a heat source in the calcining step g) for calcining the raw material, and wherein the rotary kiln exhaust gas coming from the calcining step g) is introduced into the first production line for the secondary combustion of the rotary kiln exhaust gas.

Aspects of the invention include a method of producing a cement material comprising step of: first reacting a calcium-bearing starting material with a first acid to produce an aqueous first calcium salt; second reacting the aqueous first calcium salt with a second acid to produce a solid second calcium salt; wherein the second acid is different from the first acid and the second calcium salt is different from the first calcium salt; and thermally treating the second calcium salt to produce a first cement material. Preferably, but not necessarily, during the second reacting step, reaction between the first calcium salt and the second acid regenerates the first acid.

The present invention lies within the field of construction materials and concerns a process for separating the constituents of hardened concrete, with the aim of extracting the cementitious fraction to be used in the production of thermoactivated recycled cement, involving the essential steps of: (a) crushing the concrete waste; (b) screening the crushed material to separate material smaller than about 1 mm; (c) fragmenting material larger than 1 mm; (d) screening material smaller than 1 mm into various granulometric fractions; (e) high intensity magnetic separation of the material; (f) grinding of the cementitious fraction resulting from the magnetic separation in the previous step to a size that allows its efficient thermoactivation; and (g) obtaining a thermoactivated recycled cement.

Methods for modifying a recycled fine powder of concrete and uses thereof. A method for modifying a recycled fine powder can include: crushing a collected waste concrete block step by step with a crusher, grinding with a ball mill, and passing through a 100-mesh sieve, to obtain a recycled fine powder with d50 of 13.5 μm; placing the obtained recycled fine powder in a dry environment at a high temperature, drying, then taking out, and cooling to room temperature; preparing tannic acid solutions with different concentrations, mixing the cooled recycled fine powder with the prepared tannic acid solutions, and continuously stirring by a glass rod.

Methods for modifying a recycled fine powder of concrete and uses thereof. A method for modifying a recycled fine powder can include: crushing a collected waste concrete block step by step with a crusher, grinding with a ball mill, and passing through a 100-mesh sieve, to obtain a recycled fine powder with d50 of 13.5 μm; placing the obtained recycled fine powder in a dry environment at a high temperature, drying, then taking out, and cooling to room temperature; preparing tannic acid solutions with different concentrations, mixing the cooled recycled fine powder with the prepared tannic acid solutions, and continuously stirring by a glass rod.

A method for processing material that contains cement rock may involve comminuting the material in a first comminuting device, feeding the material to a reactor in which the material is mixed with an aqueous liquid and CO.sub.2 and in which a mixing movement of the material is generated, and removing the material from the reactor and subdividing the material into at least two fractions by way of a classifying device. The temperature and the pressure in the reactor are maintained such that the pressure exceeds atmospheric pressure and such that the temperature is greater than 100° C. The method may further involve removing a withdrawal stream of the aqueous liquid from the reactor and separating and discharging suspended particles of the material from the withdrawal stream.

Aspects of the invention include a method of producing a cement material comprising step of: first reacting a calcium-bearing starting material with a first acid to produce an aqueous first calcium salt; second reacting the aqueous first calcium salt with a second acid to produce a solid second calcium salt; wherein the second acid is different from the first acid and the second calcium salt is different from the first calcium salt; and thermally treating the second calcium salt to produce a first cement material. Preferably, but not necessarily, during the second reacting step, reaction between the first calcium salt and the second acid regenerates the first acid.

Methods for modifying a recycled fine powder of concrete and uses thereof. A method for modifying a recycled fine powder can include: crushing a collected waste concrete block with a crusher, grinding with a ball mill, and passing through a 100-mesh sieve, to obtain a recycled fine powder with d50 of 13.5 μm; placing the obtained recycled fine powder in a dry environment at a high temperature, drying, then taking out, and cooling to room temperature; preparing tannic acid solutions with different concentrations, mixing the cooled recycled fine powder with the prepared tannic acid solutions, and continuously stirring by a glass rod.

Methods for modifying a recycled fine powder of concrete and uses thereof. A method for modifying a recycled fine powder can include: crushing a collected waste concrete block with a crusher, grinding with a ball mill, and passing through a 100-mesh sieve, to obtain a recycled fine powder with d50 of 13.5 μm; placing the obtained recycled fine powder in a dry environment at a high temperature, drying, then taking out, and cooling to room temperature; preparing tannic acid solutions with different concentrations, mixing the cooled recycled fine powder with the prepared tannic acid solutions, and continuously stirring by a glass rod.